Criticism is a dangerous thing to leave here. However, I am compelled.
In my opinion, all the new expansions are nothing to get excited about. Honestly approximately 95% of the "new" content is just reskins.
World events = reskinned dolmens.
Public delves = reskinned.
Dungeons = reskinned, with the occasional, minor reskinned mechanic.
Trials = reskinned, with the occasional new mechanic.
Overland content = listening to lore for hours on end.
Gear = often breaks the balance of the game.
While it is interesting to explore some new areas now and then, and the occasional cameo is also nice... the new overland stories are just not engaging. The ES Loremaster may be good at developing new lore but I cannot agree that it makes for good storytelling. Creating lore is very different from creating an engaging story.
We need characters to care about. While the companions and other characters make cameos here and there, there is usually less than one line of dialogue referencing past deeds. Creating new story arcs works when they're connected to the overall narrative.
i.e. The stories have had little to nothing to do with the Alliances since the end of those quests. Even the cameos aren't working for their alliances anymore; they are just there for the cameo affect.
Vvardenfell/Clockwork City = 2/3 three demi-gods did not even mention the Ebonheart Pact that was governing their people in any memorable way. No ripple effects from the world meld Molag Bal attempted. In my opinion, Molag Bal could've attempted to influence the demi-gods in a roundabout way and while they would've resisted, could've planted the seeds for their madness to spread; which could've led to the Saints of Asylum to go mad. Or the dolmens had some sort of influence or relation on the asteroid lingering over Morrowind.
Summerset: Three separate Daedric Princes were involved in a struggle for a powerful artifact. Molag Bal had no agent or aspect that to try to steal it; which Molag would've been motivated to do so to regain his strength that he lost at the defeat of the Vestage.
Elsweyr: Queen Aryenn has been very involved in local politics throughout her region, and yet she never made an appearance in the very loud political struggle of Elsweyr. Not even an agent of hers. Razum'Dar was on vacation and not involved in the politics at all!
Admittedly I stopped PvE story delving there. However, from what I can tell of the companions is that they're like the Pawns from Dragon's Dogma: soulless husk that just follow their master's around. It'd make more sense to just have them as hirable mercenaries. And they just make the ludicrously simple PvE overland content even easier.
Now trials and dungeons - The grind of this game is heavily focused surrounding these. So after doing hundreds and hundreds, if not thousands of dungeons... the new dungeons, and whatever reskinned or slightly changed mechanics they have, are of no interest. ZoS balancing is just making mechanics more punishing, which makes the grind to learn new dungeons even longer.
I have to say the most interesting thing I find about new content is the new public delves. They're large and often beautiful new areas, and they are usually the place that'll have the reskinned, and very rarely, new enemy types. They are worth a little exploring.
PvP - Very VERY reliant on balancing. When Sload's was a thing, I stopped playing PvP. When [snip] and decide to take a balanced class and buff it to high hells, I stop playing. PvP is very fun when classes are balanced, but in my experience playing PvP for seven years is that they are VERY rarely balanced. Balancing is a whole new zone of criticism so I'll leave that there.
World Events - The dragons of Elsweyr were one of the truly new things that I include in that 5% of new content. They were far more interesting than the Geyers of Summerset and the Vampire things of Greymoor. I would like to see this evolved upon, instead of just the volcano dolmens of the next expansion.
A large, unique legendary boss should wander around a zone, killing or trampling or scaring off the other enemy NPC's until engaged by players. The strength should be that of the dragons of Elsweyr, if not greater. Only one can spawn in game at a time, and the respawn rate should be significantly lower than that of any other world event. Enough so that when it appears, all players would like to go and help slay the creature. In order to create such an incentive, it should drop a unique cosmetic reward such as a mount, furnishing piece, momento, motif, etc. Do not have it located by any icon on the map; only that if it is discovered, players would have to call in allies by talking in zone chat or guild chat. Have it not stop wandering while being attacked, so that players will have to catch up if they're late to the party.
Now this worked well in other games because there were leveling zones. Here, everyone would have access to such a wandering event. To prevent the flooding of one zone, there'd have to be some sort of precedent for a player to be involved. We already know that there are different instances in the game, so maybe one where completion of the zone's main quest required would be where to spawn the wandering event.
Now the 5% content that was truly new includes the new classes. Warden and Necromancer. While I believe the introduction of these new classes were very poorly placed, they were new and exciting. Something worth getting excited about.
Warden - While we get reskins on literally everything in the game, I'm quite surprised that we don't get reskinned Warden animal abilities. They're all Morrowind themed, and never changed. Granting Valenwood, Summserset, Elsweyr, Marsh, Skyrim, Highrock, etc. animal packs to the Warden would revitalize the class and make replaying the class something somewhat new and exciting.
While I'm supporting reskins, add reskin packs to ALL the classes.
Dragonknight - Balrog-style animations. Dragon Leap would change the wings to a fiery shadow type. The whip ability would work well with this, but restyle it a bit along with the other classes. Shadow and fire instead of rock and scale for a lot of the Earthen abilities. Or add feathered wings in maybe a Gryphon type pack.
Templars - Fallen-style where the use of the blue blight we see in LoM could fit in well for a corrupted type.
Sorcerers - Would get creative and add some elementals familiars, and change the lightning to different elements.
Nightblade - .... Well, they're assassin/rogue types, not sure how much you can change those animations. [snip]
If ZoS is just going to resell us reskinned crap, then reskin something that we would be using a lot, and that can add a MASSIVE amount of personalization to characters. (This would be huge for the RP community, and the PvP community where the similar overpowered builds can dominate the population for months to years!)
New Sets - The sets are boring. They can easily compound to make a class incredibly powerful, or they can fizzle out completely. There really is nothing exciting about a new set, other than trying to keep a tank/healer/dps build at optimal performance. I can only suggest adding race and/or class specific sets, which I known is something ZoS has avoided. The fun loot systems that I've played before are in AARPG's like Diablo 2, but that would require such a huge overall and balancing... I cannot seriously suggest it for this game.
Elder Scrolls Online is like a cake. When ZoS tries to change something, they just change the icing's color and how it is decorated. It's still the same flavor, and it gets old real quick. And rather than building upon the original cake by adding different flavors, new decorations, and new frosting... ZoS's expansions are just the same cake, decorated differently, over and over again. It gets stale and old. If ZoS won't turn out a new cake that improves upon their original, then no one is going to return for any length of time.
Well, that is my opinion on the state of the game over the last seven years. While it has ended thousands of hours of entertainment (mostly grinding outside of PvP), I have found the game incredibly stale, lacking imagination and creativity, and not worth logging into. I do hope that it changes by adding some flavor that all would enjoy AND be an incentive for players to return.
[Edit for Bashing.]